You have to trust your surgeons, and expect that they actually do what they say -- which I am sure will be 99% of the time.
I think it more likely that the nerves can take a beating depending on how easy they are to detach from the prostate. The amount of damage can vary widely, and probably is not always evident at the time of surgery.
In your case, it's safe to assume not much damage
Age 63. Other than cancer, in good health; BMI 20